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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 154 |
| 4 | 66344 |
| 5 | 15471166144 |
| 6 | 663447306235471066144 |
| 7 | 1547116614473162154311663447306215471066144 |
[1,6,154,66344,15471166144,663447306235471066144, 1547116614473162154311663447306215471066144] |